The present invention has been developed on the basis that prior art defined distribution transparencies are not sufficient to support mobility.
More specifically the present invention has been developed on the basis of considering mobility as an additional transparency.
In other words, the invention suggests the provision of the mobility support functions in a transparent way, i.e. the application designer needs not to be aware or concerned about the necessary mechanisms and function to support mobility and can concentrate on his application design. Mobility can hence be considered as a new transparency in addition to the ones defined by ODP (Open Distributed Processing) [ITUa] and adopted by TINA (Telecommunication Information Networking Architecture) [TIN95i].
According to ODP/TINA, a telecommunication application is realized by a set of interacting computational objects which rely on an abstract infrastructure called Distributed Processing Environment (DPE). The DPE hides the complex details of mechanisms used to overcome problems caused by distribution.
The process of hiding the effect of distribution is known as distribution transparency in the Open Distributed Processing Reference Model (RM-ODP). The application designers do not need to be aware of the mechanisms necessary to deal with different aspects of distribution and can therefore focus on their application specification. When addressing the distribution of their applications, they only have to express their requirements for transparencies. The properties of distribution is hidden or transparent to the end-users and the application designers in the enterprise, information and computational viewpoints.
The engineering viewpoint defines the mechanisms and functions by which those transparencies are realised. Each set of transparency properties requires the use of a set of standard functions in a specified way.
The distribution transparencies defined by ODP/TINA are:                Access transparency        Location transparency        Federation transparency        Migration transparency        Transaction transparency        Replication transparency        Failure transparency        Resource transparency        Concurrency transparency        
As shown in FIG. 1, a DPE consists of several DPE nodes A, B and C. A DPE node is a unit of resource administration providing support to the DPE architecture. The part of the DPE node supporting the DPE architecture is called a DPE platform. The computing resource supporting a DPE platform is called Native Computing and Communication Environment (NCCE). Even if the NCCE can itself be locally distributed, there is only one DPE platform associated with a DPE node.
A DPE platform shields the objects from the potential heterogeneity of the NCCE on which they are executed. Not all the transparencies are required to be provided by a DPE platform but only the ones called fundamental. Access transparency and location transparency are the two transparencies which are considered fundamental in the DPE architecture.
Mobility support functions are implemented and offered in different systems such as UPT (Universal Personal Telecommunication) and networks such GSM (Global Mobil System) but never in a transparent way. In order to build new application, the designers must take into account and know fairly well about the mobility support functions. ODP/TINA introduced an efficient framework for designing and implementing distributed applications but assume that mobility is inherently supported. In fact, mobility is not inherently supported. When a terminal which is a DPE node is moving, disappearing and reappearing some moment later at another place, additional mobility functions must be introduced and preferably in a transparent way. In other words, mobility transparency is required.
The design of mobile applications, i.e. applications available to the mobile users, is complex and time-consuming because the designer has to take into account mobility functions which are quite complex and numerous. It is also difficult and time-consuming to make existing fixed applications available to mobile users, i.e. mobile without mobility transparency.